The present invention relates to forming a dielectric layer by thermal decomposition of a metallo-organic material.
Ceramic oxide layers are diverse in their properties. Apart from their unusually high mechanical strength, high wear and abrasion resistance, and high corrosion resistance, they can be considered to be dielectric, ferroelectric, piezoelectric, or optoelectronic materials. They can also be utilized in both electrical and thermal insulation applications. These ceramic oxides can be crystalline or amorphous.
Layers of ceramic materials can be manufactured using physical vapor deposition (PVD) and chemical vapor deposition (CVD), laser ablation, dip and knife coating of a ceramic precursor material, and metallo-oxide decomposition (MOD) as shown by Mir et al in commonly-assigned U.S. Pat. No. 4,880,770.
Formation of dielectric material normally requires high temperature processing. This high temperature processing restricts the choice of substrates that can be selected for use. Capacitors are multilayer coatings comprised of an arrangement of conductive, dielectric, and conductive layers in sequence. There is a need for forming dielectric materials on a substrate in many applications such as capacitive devices. Capacitors are essentially materials with high dielectric constants. Dielectric (which is essentially electrically non-conducting) characteristic of ceramic materials are well known and getting increasing importance as the field of solid state electronics continues to expand rapidly. The principal applications for ceramic dielectrics are as capacitive elements in electronic circuits and as electrical insulation. For these applications, the properties of most concern are the dielectric constant, dielectric loss factor, and dielectric strength. The principal characteristics of a capacitor are that an electric charge can be stored in that capacitor and the magnitude of the charge which can be stored is dependent primarily on the nature of the material, grain size, and the impurity distribution at the grain boundaries.
Scratches are associated with soft materials and in many cases makes an object unacceptable for use. Some of the materials that require an absence of any significant scratch component includes, lenses, photographic films, paper, polymers, metals, metal coated polymers, magnetic recording media and the like. There is a need for forming such protective layers at low temperature in order to take advantage of the many unique substrates in existence.
It is an object of the present invention to provide a method for forming a dielectric on a substrate, which can be used in many different types of articles.
This object is achieved in a method of forming a dielectric layer on a substrate, comprising the steps of:
(a) providing a metallo-organic material in a solvent, which dissolves such metallo-organic material;
(b) coating dissolved metallo-organic material onto the substrate to form a layer; and
(c) heating the deposited layer in an oxygen environment to produce thermal decomposition of the organic component of the dissolved metallo-organic material and a reaction of the metallic portion of the material with oxygen thereby causing the layer to become dielectric.
The present invention is particularly suitable to provide a dielectric layer for an article and also to provide a scratch resistant layer on metals, alloys, polymers, organics, inorganics, composites, glasses, paper, photographic film, magnetic media, and ceramic substrates.
Another feature of the invention is that the present method can produce articles at a low temperature so that the substrates are not adversely affected by the process of formation of the article.
This invention provides a convenient way to have fully completed solid state reactions to produce desired chemistries in material layer. It is easy to control various crystallographic phases of the material by simplified doping methods.
The method described in this invention is a simple technique for layer deposition with low cost equipment requirements, and permits excellent control of overall stoichiometry, high uniformity of thickness and composition, and ability to coat irregular substrate shapes in a cost effective manner.
A feature of the present invention is that it permits a low temperature process, allowing in-situ processing of temperature sensitive devices and can produce hard and tough layers/films, which have high wear and abrasion resistance.
This invention overcomes many of the problems that are associated with conventional methods of fabricating multilayer capacitors, flexible capacitors, scratch resistant lenses, capacitors integrated onto circuit boards, and protective coatings on metals, alloys, polymers, organics, inorganics, composites, glasses, paper, photographic film, magnetic media, and ceramic substrates both flexible and rigid in form.